 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui;

 /**
  * An adapter which performs action filtering.
  * <p>
  * Within the workbench a plugin may extend the actions which appear in the
  * context menu for any object. The visibility of each action extension is controlled
  * by action filtering. By default, the workbench will filter each action extension using
  * the <code>objectClass</code> and optional <code>nameFilter</code> attributes defined
  * in xml. If the action extension passes this test the action will be added to the
  * context menu for the object.
  * </p>
  * <p>
  * In some situations the object class and name are not enough to describe the intended
  * target action. In those situations an action extension may define one or more
  * <code>filter</code> sub-elements. Each one of these elements describes one attribute of
  * the action target using a <code>name value</code> pair. The attributes for an object
  * are type specific and beyond the domain of the workbench itself, so the workbench
  * will delegate filtering at this level to an <code>IActionFilter</code>. This is a
  * filtering strategy which is provided by the selection itself and may perform type
  * specific filtering.
  * </p>
  * <p>
  * The workbench will retrieve the filter from the selected object by testing to see
  * if it implements <code>IActionFilter</code>. If that fails, the workbench will ask for
  * a filter through through the <code>IAdaptable</code> mechanism. If a filter is
  * found the workbench will pass each name value pair to the filter to determine if it
  * matches the state of the selected object. If so, or there is no filter, the action
  * will be added to the context menu for the object.
  * </p>
  * <p>
  * Clients that implement this filter mechanism are strongly encouraged to extend this
  * interface to provide a list of attribute names and possible values that are
  * considered public for other clients to reference.
  * </p>
  *
  * @see org.eclipse.core.runtime.IAdaptable
  */
 public interface IActionFilter {
     /**
      * Returns whether the specific attribute matches the state of the target
      * object.
      *
      * @param target the target object
      * @param name the attribute name
      * @param value the attribute value
      * @return <code>true</code> if the attribute matches; <code>false</code> otherwise
      */
     public boolean testAttribute(Object target, String name, String value);
 }

